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Avulsion
fractures occur most commonly in adolescent athletes as a result of abnormal
stress placed on the tendinous attachments of muscles. Prior to fusion
of the ossification centers, the growing apophysis is more likely to become
injured than the adjoined tendons. The most common sites of avulsion occur
in the pelvis where the muscles with the greatest strength are attached.
The most
common locations:
- iliac crest: transversalis,
internal oblique and external oblique muscles
- anterior superior
iliac spine: sartorius muscle
- anterior inferior
iliac spine: rectus femoris muscle
- ischial tuberosity:
hamstring muscles (biceps femoris, gracilis, semimembranosus and semitendinosus)
- lesser trochanter:
iliopsoas muscle
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Avulsion
injury of the right ischial tuberosity in a 14-year-old boy. Radiograph
shows lateral displacement of a right ischial tuberosity fragment (arrow)
likely secondary to an avulsion fracture involving the biceps femoris. |
| Avulsion type fracture
of right anterior inferior iliac spine in a 14-year-old male sprinter.
Left, AP view of right hip reveals bony fragmentation inferior to
the iliac spine and lateral to the femoral head. Right, Coronal MR
through pelvis shows increased signal in the right anterior inferior
iliac spine at the site of insertion of the rectus femoris muscle,
consistent with an avulsion fracture. |
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